In a silver halide photographic material, a photographic emulsion layer and the other hydrophilic colloid layers are often colored for the purpose of absorbing a light of a specific wavelength range.
When it is necessary to control a spectral composition of a light incident to a photographic emulsion layer, a colored layer is usually provided farther from a support than the photographic emulsion layer. Such a colored layer is called a filter layer. Where more than one photographic emulsion layer are involved, the filter layer may be interposed between them.
For the purpose of preventing a fuzziness of an image, that is, a halation caused by light which is scattered in or after passing through a photographic emulsion layer and is reflected on the interface between the emulsion layer and support or the surface of a support side opposite to the emulsion layer to get once again in the photographic emulsion layer, a colored layer called an anti-halation layer is placed between the photographic emulsion layer and support or on the support side opposite to the photographic emulsion layer. When one or more photographic emulsion layers are involved, the anti-halation layer may be interposed between them.
The photographic emulsion layer is sometimes colored in order to prevent the deterioration of an image sharpness (in general, this phenomenon is called "irradiation") caused by a light scattered in the photographic emulsion layer. Dyes are usually incorporated into these layers to be colored. These dyes should satisfy the following conditions:
(1) having an appropriate spectral absorption according to use purposes;
(2) being photochemically inactive, that is, causing no bad chemical effects such as, for example, reduction of a sensitivity, degradation of a latent image and fogging to the characteristics of a silver halide photographic material;
(3) being able to be bleached in photographic processing steps or eluted in a processing solution or water for washing so as to leave no harmful color on a processed photographic material;
(4) not diffusing from the colored layer to other layers; and
(5) having an excellent aging stability while in solution or in the photographic material and not discoloring or fading.
In particular, when a colored layer is a filter layer or an anti-halation layer provided on the same side of a support as the photographic emulsion layer, it is often necessary for those filter or anti-halation layers to be selectively colored and for the other layers to not be substantially colored; otherwise not only would a harmful spectral effect be exerted on the other layers, but also the intended effect of the filter layer or anti-halation layer is reduced. However, a layer containing a dye, when wet, contacts other hydrophilic layers and often results in a part of the dye being diffused from the former to the latter.
Many efforts have so far been made to prevent such a diffusion of the dye. For example, such methods are disclosed in U.S. Pat. Nos. 2,548,564, 4,124,386 and 3,625,694, in which a hydrophilic polymer having a charge opposite to a dissociated anionic dye is permitted to coexist as a mordant in a layer to localize the dye in a specific layer by means of an interaction with a dye molecule.
Further, the methods in which a specific layer is colored with a water insoluble solid dye are disclosed in JP-A-56-12639 (the term "JP-A" as used herein means an unexamined published Japanese patent application), 55-155350, 55-155351, 63-27838, and 63-197943, European Patents 15,601, 274,723, 276,566 and 299,435, U.S. Pat. No. 4,803,150, and Published International Patent Application (WO)88/04794.
Furthermore, methods are disclosed in U.S. Pat. Nos. 2,719,088, 2,496,841 and 2,496,843, and JP-A-60-45237 in which a specific layer is colored with fine metal salt particles on which dyes are adsorbed.
However, even if these improved methods are used, the decoloring speed for development processing is still so slow and it creates a problem. The decoloring function does not necessarily occur when various factors are changed; such factors include conversion to a rapid processing, improvement in the composition of a processing solution and improvement in the composition of a photographic emulsion.